Background and Purpose-We sought to examine the frequency, predictors, and effects of nontreatment with antithrombotic and antihypertensive therapies 3 months after ischemic stroke. Methods-The population-based South London Community Stroke Register prospectively collected data on first-in-alifetime strokes between 1995 and 1997. Among patients registered with ischemic stroke, treatment status with antithrombotic and antihypertensive therapies was examined 3 months after the event. Results-In a cohort of 457 patients with ischemic stroke, 393 (86.0%) were considered appropriate for antiplatelet medication, 32 (7.0%) for anticoagulant medication, and 254 (55.9%) for antihypertensive medication. The rates of nontreatment observed 3 months after the event were 24.4% for antiplatelet, 59.4% for anticoagulant, and 29.5% for antihypertensive medication. Independent risk factors for nontreatment with antithrombotic therapies (antiplatelets and anticoagulants) were the subtype of stroke (nonlacunar infarct: ORϭ1.60, 95% CI 1.07 to 2.54), stroke severity measured by the Glasgow Coma Scale (GCS) score (GCS Յ13: OR 2.08, 95% CI 1.18 to 3.66) and the Barthel Index (BI) score 5 days after the event (BI Յ10: OR 1.85, 95% CI 1.17 to 2.93). For antihypertensive therapies the stroke subtype (OR 2.46, 95% CI 1.33 to 4.54), GCS score (OR 2.97, 95% CI 1.35 to 6.53), BI score (OR 2.33, 95% CI 1.27 to 4.29), and ethnicity (Caucasian: OR 2.43, 95% CI 1.15 to 5.14) were independently associated with nontreatment. Cox regression modeling showed no significant association between the treatment status and recurrence-free 3-year survival rates after controlling for severity and subtype of stroke. Conclusions-Secondary prevention for a common disease such as stroke appears to be inadequate in the study area.Healthcare professionals need to consider antithrombotic and antihypertensive therapies for all stroke patients. (Stroke. 2000;31:469-475.)